Usually, as this kind of head-up display apparatus, one described in Patent Document 1 below has been known. With such a head-up display apparatus, it is also possible to use a combiner, and a reflecting member, of the head-up display apparatus in imaging a user by disposing an imaging device which captures an image of the user in the optical axis of the head-up display apparatus, thereby to reduce the number of dedicated members required for the imaging, captures an image of the user (particularly the user's face) with a simpler configuration, and calculate an eye position of the user. A result of the determination of the user's eye position is applicable not only to a display image position adjustment disclosed in Patent Document 1, but to a detection of a line or point of sight of the user and a determination of a condition of the user such as looking aside or falling asleep while driving.
Patent Document 1: JP-A-8-156646